Content System
Delivering content to different mobile phones is a complicated and painstaking task. Luckily, your life was made easier, by us! Our content system takes your mobile content and serves it to your consumers, dynamically choosing the correct format for the viewing device. So how do we do it? Read on...
Images
For images, we take your uploaded content and host it on our server. When the user
accesses the dynamic content link (?) we pass the request on to our media adapter,
which will identify the viewing device and look up what image formats it supports
and its screen size. It then dynamically, will adapt the image using the imagemagick
open source library to the correct format and size.
Audio
Since audio transcoding is often more processor intensive then images, we take care
of converting your content ahead of time, in fact, as soon as you upload the file.
Using a modified build of the open source Ffmpeg library, we make sure the file
is converted to all the different specifications to reach as many handsets as possible.
Take a look at the chart below to understand the different file formats.
| Format | Channels | Bit Rate | Frequency |
|---|---|---|---|
| AAC | 1 | 64k | 48000 Hz |
| AMR | 1 | 12.2k | 8000 Hz |
| MP3 | 1 | 64k | 44100 Hz |
| QCP | 1 | 64k | 44100 Hz |
| WAV | 1 | 64k | 44100 Hz |
Once a request for an audio type content comes in, we again identify the handset and its specs and choose the correct file version and format for that handset.
Video
Video is similar to audio. All the heavy lifting is taken care of at upload time,
again using ffmpeg. We've spent many long hours making sure that the video file
is converted to the minimum number of formats to reach as many handsets as we can.
If you've ever tried to play with video transcoding, you'll feel our pain. There
are many different combinations of video and audio codecs, combined together in
many different types of containers, not to mention all the configurable parameters.
For more information, read this wikipedia article about video containers.
So we've been able to narrow down the conversions to the formats listed below.
| Format | Vcodec | Acodec | Size | Audio Channels | Audio Bit Rate | Audio Frequency | Video Bit Rate |
|---|---|---|---|---|---|---|---|
| 3GP | H263 | AMR | Default | 1 | 12.2k | 8000 Hz | 200 kb/s |
| 3G2 | MPEG4 | AMR | Default | 1 | 12.2k | 8000 Hz | 200 kb/s |
| MOV | H263 | AMR | Default | 1 | 12.2k | 8000 Hz | 200 kb/s |
| MP4 | MPEG4 | MP3 | Default | 1 | 64k | 48000 Hz | 200 kb/s |
| WMV | WMV2 | AAC | 320x240 | 2 | 56k | 44100 Hz | 1000 kb/s |
This means that we have a format ready for any video supported device that may want to view your content.
Upload Restrictions
So knowing all this, what type of file should you upload? We recommend uploading an mp3 or wav file for audio, no bigger than 500kb, which should be equivalent to about 30 secs of average quality audio. For video, upload the file in either mp4 or 3gpp formats, these are the best quality for compression ratio. Again, try to keep it below the 500kb mark, or 30 secs in length.
The reason for this is that most users in the world today still pay hefty data charges, and on a prepaid phone plan in the US, with data, a 1.5 mb video will cost the average user about $15 (USD). As time goes by, data caps and unlimited plans will become more commonplace (a la the iphone on AT&T in the US), so bigger content files will cost your consumers less.
All this being said we don't restrict uploaded content file size programmatically, so upload more bytes at will!
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